A. Field of the Invention
The present invention relates to an actuating mechanism for a flap system for an aircraft having an upper surface blowing powered lift system.
B. Brief Description of the Prior Art
In recent years, increasing attention has been given to aircraft designs having the capability of efficient cruise at relatively high speeds, and also having the ability to take off and land in relatively short distances. Such airplanes are generally referred to as "STOL aircraft" (i.e. short take-off and landing aircraft). To develope adequate lift for the aircraft at low speed operation, such STOL aircraft commonly utilize the jet exhaust from the engines in combination with a flap system on the wing to divert the exhaust downwardly and thus increase lift.
One method of doing this is by blowing the jet exhaust over the upper surface of the wing, and utilizing downwardly extending trailing edge flaps to divert the exhaust downwardly by the Coanda effect. One such aircraft is shown in U.S. Pat. No. 3,977,630, Lewis et al, this patent being assigned to the assignee of the present invention. In the apparatus shown in that patent there is a high mounted wing, and a pair of mixed flow turbofan engines mounted on the wing to discharge their exhaust streams chordwise over the upper surface of the wing. There is a pair of trailing edge flaps, one behind each engine. The more forward flap of each pair is mounted on a first arm for rotation in a circular arc about a first axis of rotation. The rear flap of each pair is mounted to a second arm which is in turn mounted for rotation in a circular arc about an axis on the first arm which supports the forward flap.
Each pair of flaps has a stowed position where the flaps fit into a cove section at the aft end of the wing, and a deployed position where the two flaps are rotated downwardly and rearwardly. At the forward end of each flap is a small panel, with these panels being able to be moved to an upper position where they form with the upper surface of the wing and the upper surface of the two flaps a continuous aerodynamic surface. These two panels can also be moved to a down position to open slots at the forward ends of their two flaps. Thus, in the event of a loss of power, the panels of the flaps can be moved to the position to open the slots, thus decreasing drag on the wing.
With the two pairs of flaps in their fully deployed position, and with the flap panels closed, they define a downwardly and rearwardly curving aerodynamic surface at the trailing edge of the wing. The jet exhaust being discharged over the upper rear edge of the surface of the right and left wings follows this downwardly aerodynamic contour provided by the two pairs of flaps due to the Coanda effect, to develop a downward thrust.
With regard to the prior art disclosed in other U.S. patents obtained from a search of the patent literature, the following are noted:
U.S. Pat. No. 3,259,341, Steidel, discloses a concept for an airfoil where air is blown from within the wing over the upper surface of a trailing edge flap. The trailing edge flap is mounted for rotation at a location within the forward knee portion of the flap.
U.S. Pat. No. 3,438,599, Welzen, discloses an airfoil with a trailing edge flap which is moveable on a curved track from a stowed to a deployed position.
U.S. Pat. No. 3,614,028, Kleckner, discloses a STOL aircraft where a portion of the efflux from the fan section of a jet engine passes over the wing of the aircraft while the main discharge of the jet engine passes under the wing. The trailing edge flap is utilized to direct the jet flow downwardly for STOL operation. The flap is mounted to rotate about a radius point positioned below the forward knee portion of the flap, and the flap is rotated about this radius point downwardly and away from the trailing edge of the wing to form a slot between the forward end of the flap and the trailing edge of the wing.
U.S. Pat. No. 3,778,009, Jones, discloses a trailing edge device having a pair of members which can be extended or inflated to produce what is described generally as a semicylindrical profile. The forward member is mounted to a track for travel over a curved path.